This invention relates to an automated process for the manufacture of lead-acid batteries and an associated apparatus and new features of battery design and construction resulting therefrom. More specifically, this invention pertains to an improved lead-acid battery and an efficient method and associated apparatus for its manufacture in a large variety of shapes and sizes for uses such as automotive starting, traction, industrial, and small sealed lead-acid battery applications.
Lead acid batteries are a well known source of energy. The conventional lead-acid battery consists of a plurality of positive plates and a plurality of negative plates separated by porous separators. Conventionally, each positive and negative plate comprises a supporting conductive grid structure which is normally made of lead or a lead alloy and which supports an electrochemically active paste material. The lead grids serve the dual purpose of supporting the paste material as well as acting as electrical current conductors.
The lead acid battery plates are made by pasting a leady oxide material over the lead wire grid. Separate positive and negative plates are pasted and cured, with each of the plates having a lug disposed on the top portion of the plate. Prior to being placed in the battery container, a separator is placed between each plate and the negative and positive plate lugs are joined by two separate plate straps, one for the positive plate lugs and one for the negative plate lugs. Once placed into the container the intercell connections are made and the battery container and cover are sealed together. The positive and negative posts are welded in the cover, the acid is added, and the battery is formed electrochemically.
As is well known, the chemical reaction between the battery plates and the acid produces an electric charge which can be used to start an automobile, for example. The chemical reaction is reversible so that a generator in an automobile, for example, can recharge the battery.
There are many known processes for making lead-acid batteries. One known process is disclosed in U.S. Pat. No. 4,271,586. This process involves feeding a ribbon of lead into an inline expander (such as is described in U.S. Pat. No. 3,853,626) to produce a continuous bilateral length of grid making stock. The stock has a central unexpanded strip and two unexpanded strips at the lateral edges thereof. Between the central unexpanded strip and each lateral edge, there is a network of grid wires formed by the expander. The battery grid-making stock enters a belt paster for filling the battery grid network with battery paste. The pasting machine sandwiches the battery grid making stock and paste between paper strips fed from paper rolls. Battery plate forming stock exits the paster and passes into an oven for flash drying. Following flash drying and cutting, the battery plate forming stock is ready for curing. After curing, a stacker accumulates the battery plates for subsequent processing into a lead-acid battery.
The subsequent processing involves making a battery element out of the negative and positive battery grids and the separators. After this, the positive lugs of the battery grids and the negative lugs of the battery grids are separately joined by exposing each of them to molten lead, which subsequently hardens to form the plate strap. The battery grids are then placed into the container, the intercell connection made, and the battery container and cover are sealingly joined. Finally, the posts are formed on the battery cover.
The present invention relates to a highly commercial acceptable process and apparatus for continuously making and expanding lead grids for a lead-acid storage battery from a narrow sheet or strip of lead utilizing a modified in-line, dual expansion guillotine process and the grid produced is satisfactory for commercial manufacture and customer use. The grids made by this invention are useful with both positive and negative battery plates.
Presently, there are many different techniques for fabricating current collectors including subjecting a lead substrate to mechanical expansion and perforating the lead substrate, thereby creating the battery grid. However, mechanically expanded lead plates that are perforated often have burrs which are potential contributors to battery shorting.
It would, therefore, be advantageous to provide a method and apparatus for producing lead plate battery grids for a lead acid storage battery which has less burrs, thereby, reducing failures from shorts.
Therefore, it would be desirable to provide an improvement, which overcomes the aforementioned inadequacies of the prior art and provides a significant contribution to the advancement of the art of battery plate production.
Accordingly, what is needed in the art is an improvement for manufacturing battery grids in both the geometry of the battery grid design as well as in the battery grid wire structure.
It would be further desirable to provide a method and apparatus for producing an improved battery grid with reproducible results.
It would also be desirable to provide a method and apparatus for enhancing both electrical efficiency and castability of the battery grid.
It would also be desirable to provide a method and apparatus for improving the battery grid that can easily be adapted to current manufacturing techniques.
It would also be desirable to provide a method and apparatus for economically continuously producing battery plate grids over a wide range of lead alloys and metal contents.
It would be further desirable to provide a method and apparatus for improving the battery grid that involves feeding a lead strip onto a frame between opposing rows of progressive dies and cutters.
It would also be desirable to provide a method and apparatus for improving the grid by punching an alignment hole into the lead strip during the expanding and cutting process.
It would also be desirable to provide a method and apparatus for improving the battery grid by aligning the lead strip through the use of at least one alignment pin into at least one of the alignment holes in the lead strip.
It would also be desirable to provide a method and apparatus for improving the battery grid that employs an indexing mechanism that advances the lead strip an indexed distance corresponding to the distance the lead strip moves during the expanding and cutting process.
In accordance with one aspect of the present invention, there is provided method and apparatus for manufacturing an improved battery plate.
In one preferred embodiment of the present invention, the method of making lead-acid storage battery plates comprises the step of aligning a lead strip as it is progressively expanded and cut into a grid pattern on an expander die system. Specifically, the lead strip is fed onto a frame between opposing rows of progressive dies and cutters. An alignment hole is punched into the lead strip each time the lead strip is progressively indexed on the frame between opposing rows of progressive dies and cutters. The alignment step is accomplished by inserting at least one alignment pin into at least one of the alignment holes that have been punched into the lead strip as the lead strip is progressively expanded and cut into a plurality of wire-like segments along opposing edges of the lead strip. After each cut, the alignment pin retracts while the lead strip is indexed.
In another exemplary embodiment of the present invention, the apparatus for use in the manufacture of plates for a lead-acid storage battery in a continuous operation, comprises an alignment means for aligning a lead strip as it is progressively expanded and cut into a grid pattern. Specifically, a lead strip is placed onto a frame having a first end, a second end and a series of progressive dies and cutters positioned longitudinally along the frame. An alignment puncher is provided for punching an alignment hole into the lead strip each time the lead strip is progressively indexed on the frame between opposing rows of progressive dies and cutters. An indexing mechanism advances the lead strip an indexed distance corresponding to the distance the lead strip moves during the expanding and cutting process. At least one alignment pin is provided which projects into at least one of the alignment holes in the lead strip for aligning the lead strip during the expanding and cutting process. The alignment pin retracts during the indexing of the lead strip.
A feature of the present invention is to provide an alignment puncher at the first end of the frame and an indexing mechanism at the second end of the frame.
Another feature of the present invention is to provide an indexing mechanism that is a linear feeder.
Still yet another feature of the present invention is to provide an indexing mechanism that is easily adaptable to the present technology for expanding and cutting lead strip into battery grid.
Another feature of the present invention is to provide a plurality of alignment pins that are spring controlled, thereby allowing the plurality of alignment pins to reposition the lead strip as the alignment pins are inserted into the alignment holes.
Yet another feature of the present invention is to provide an indexing mechanism along the centerline of the lead strip.
The foregoing has outlined rather broadly the more pertinent and important features of the present invention in order that the detailed description of the invention that follows may be better understood so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.